In the field of woodworking, those skilled in the art of plane making seek to secure the blade of a plane, referred to as a plane iron, as rigidly as possible in order to prevent chatter, achieve smooth cuts, and set and maintain a desired depth of cut. In the simplest construction, the plane iron is held by means of a wedge driven between a forward section of the body and the plane iron, which creates pressure against a ramp. The wedge is positioned into shallow grooves that are cut into a throat and tapered toward a mouth, where the taper is matched to a pitch of the wedge.
In a slightly different design, the plane body utilizes a retaining pin passing transversely through a body of the plane through a throat of the plane body and parallel to a sole of the plane body. A plate, known as a cap iron, pivots against a retaining pin and contacts the plane iron close to a cutting edge at a mouth of the plane body. A screw is positioned opposite the mouth and on the other side of the retaining pin, where the screw is threaded through the cap iron and is turned to create leverage against the plane iron on either side of the pin. Other prior art devices using this design lever the cap iron on the screw fastened into the plane body at the ramp. A cutting depth of the plane iron is adjusted by means of a slot in the plane iron running longitudinally. A hole in the cap iron captures the head of the screw, using it as a fulcrum to lever the plane iron firmly against the ramp. In each of these prior art devices the front and rear sections are integral with sides that encompass the plane iron, which allows it to plane only a portion of the total width of the plane body as it projects through the sole.
Another class of planes, know in the art as rabbeting planes, are designed to cut the entire width of the plane body by means of openings in the sides of the body. The plane iron is then formed with a full width edge that can project past the side openings, but a narrower tang portion is necessary to fit between raised sides, the higher sides being necessary to hold the front and rear portions of the sole in alignment, and the tang necessary for clamping and depth adjustment.
Various embodiments provide a method and apparatus for a blade clamping mechanism in a woodworking plane, which allows a plane iron as wide as the plane body itself to be clamped in a wedge shaped slot in the plane body. The slot begins at a point tangent to a waste ejection hole at the front of the plane and runs diagonally towards the spine of the plane body, looping back short of the spine and returning diagonally through the sole forming the mouth together with the waste hole. The loop forms the widest point of the slot and the tangent forms the narrowest point of the slot, where the rear surface of the slot serves as the ramp for the plane iron. The plane iron is clamped by a floating pin mounted in a hole drilled longitudinally through the spine, perpendicular to the ramp, and terminating at an inspection hole. The floating pin is retained between the under side of the plane iron and the conical shaped point of a screw threaded from the back of the plane body diagonally to the pin and parallel to the sole. The pin and the screw contact and are viewable through the inspection hole.
In use the blade is adjusted to the desired depth while the pin is loose. As the screw is advanced the pin is tightened against the under side of the blade flexing the blade against the tangent point of the waste hole. Within the confines of the wedge shaped slot as the pin climbs, the conical tip of the screw at a compounded ratio thereby places sufficient clamping pressure at the mouth of the plane.
Other embodiments provide a rabbeting plane comprising a plane body and a plane iron. The rabbeting plane further comprises a slot extending partially through the plane body into which the plane iron is received. The rabbeting plane further comprises a first hole extending from an edge of the plane body to an interaction area and a second hole extending from the interaction area to the slot. Finally, the rabbeting plane further comprises a pin extending from the interaction area to the slot through the second hole positioned so as to engage the plane iron and a screw extending from outside the plane body to the interaction area through the first hole, an end of the screw interacting with an end of the pin such that the pin secures the plane iron to the plane body.
Other aspects of the embodiments are numerous. The instant blades do not require tangs and may be made the full width of the plane body. This enables planes to be formed much narrower than other planes, which are then able to cut in tighter spaces. As the plane iron cuts full width, they may be formed and ground to cut many different profiles. It is easier to manufacture these planes in smaller sizes for fine detail cutting and miniature work. The clamping force is compounded and focused at the mouth of the ramp and blades do not chatter due to looseness at the mouth.